Multiple <ui:debug /> tags on one view page with input elements will cause Internet Explorer to display a "Out of memory" dialog box, when the user wants to enter some text into the input field.
The dialog box can be clicked away and the input stays in the input field. Obviously this is very annoying since the dialog box will pop up after each key stroke.
One can argue, why to put multiple <ui:debug /> tags on one page - I agree - no sense at all, but it can easily happen when using template pages and compositions.
This may or may not be a bug and can easily be avoided. I just wanted leave a pointer for someone encountering strange error dialog boxes while using IE.